Because of such preferable properties as high impact strength and high elongation, thermoplastic resins such as ABS resins and polycarbonate resins are utilized in various fields as molding materials for a variety of purposes, including of course automobiles and household electric appliances. However, where test resin moldings or resin molding products varied in kind but small in quantity are intended to be manufactured by using such resins as mentioned above, for example, ABS resins, no viscosity of the resin adaptable for use in cast molding technique is obtained even when the resins are heated to about 280.degree. C. and, therefore, no desired resin moldings can be manufactured therefrom by the casting technique. Thus, there is left no alternative but to manufacture desired resin moldings from these resin by injection molding or the like techniques. On that account, there was such a problem that the manufacturing of the above mentioned resin moldings from these resins relying on the injection molding or the like molding techniques cannot be exempted from such an economical disadvantage as the use of expensive metal molds or the like.
On the one hand, the aforesaid test resin moldings or resin molding products varied in kind but small in quantity can be manufactured at a very low cost from thermosetting resins such as epoxy resins since these theremosetting resins are in the form of monomers or oligomer when they are molded and are moldable with silicone molds or simple metal molds according to the casting technique. In cured products of thermosetting resins, however, there were involved such problems that the cured products are generally poor in physical properties such as impact strength and elongation, and are found to be fragile, and particularly it was found that it was difficult to obtain resin molding products having an Izod impact strength of higher than 10 kg cm/cm. Mixing thermosetting resins with such flexibility imparting agents as rubber and the like for the purpose of improving the cured products of said thermosetting resins in such physical properties as mentioned above inversely resulted in a further problem that said cured products as obtained thereby are extremely decreased in tensile strength, flexural strength, compression strength, heat resistance or the like properties; finally, according to such procedure no resin molding products can be obtained which are excellent in the balance of various desired physical properties.
In this connection, the specification of British Patent No. 1,087,166 discloses a process for preparing polyether resins having a molecular weight of at least 40,000. According to this patent specification, it is alleged that the desired polyether resins are obtained by reacting bisphenols or divalent phenols with diepoxy compounds in the presence of tertiary amine catalysts.
Even the polyether resins as obtained in examples of the specification of this British patent, however, still involved therein such a problem that said polyether resins cannot be said to be excellent in the balance of various physical properties such as impact strength and the like.